Fireproof wiper roll



Dec. 24, 1946.

R. A. LARSON FIREPROOF W IPER ROLL Filed July 15, 1943 luncntor 62 4 6 ,4. Larva/7 dltorucgs.

Patented Dec. 24,

umrs,

2,413,146 mnrnoor WIPERBOLL Ralph A. Larson, Oak Park. 111., assignor to (Jontinental Can Company, Inc., New York, N. Y a corporation of New York Application July 15, 1943, Serial No. 494,875 3 Claims. (Cl. -230) In the quantity production of can bodies by 'machine, a practice has been to form the can between the successive layers of the hooks. This operation causes deposit of a considerable quantity of solder at the sides of the crevice: and a practice has been to employ a wiper roll for removing this excess solder prior to the cooling below the temperature of fluidity. Important savings of cost have been eflected by recovering this excess solder.

This assembly is effective with employment of the usual lead-tin solders, as the melting point is relatively low and does not substantially exceed the temperature of thermal decomposition of organic materials. Hence the wiper rolls may be made'of cotton disks, and therewith have the desired softness or flexibility so that they are capable of yielding for conforming to the surface of the can, and'of serving to remove the excess solder.

When it is sought to employ solder.of high melting point, particularly solders made from lead-silver alloys, the fusion temperature is well above the decomposition point of such organic substances. Whereas the normal wiper roll may be used over a long period of time before it is destroyed by wear during employment of the tin-lead solders, it has been-found that such wiper rolls do not last with lead-silver solders, due to decomposition, production of inflammable volatiles, and ignition at temperatures necessarily used.

It is necessary that the wiper roll be flexible for conforming to the can body surface, and that it be able to withstand mechanical wear. These considerations have ruled out the possibility of employing asbestos rolls of filamentary or bonded asbestos.

It has similarly been found that many of the fire-proofing and saturating solutions, employed to prevent decomposition of organic materials, do not produce wiper rolls which have adequate resistance to ignition, on the one hand, and which have the requisite softness and flexibility, on the other hand.

It has been found, in accordance with the present invention, that a, wiper roll of satisfactory characteristics can be produced by saturating an organic textile such as cotton cloth, linen cloth, or other fiber cloth of cellulosic structure, with fire-proofing solution, forming and drying the roll, and then manipulating the material to give the desired softness and flexibility. These opera- -tions may be performed upon the cloth before cutting and assembling into rolls, or they may be performed after the cloth has been cut and collected to form the roll.

' As an example-of practice, cotton cloth was cut into disks which were superimposed to form,

a pile. The disks may then be stitched together. The assembled wiper roll is immersed for ten minutes in fire-proofing solution of the following formula:

Per cent by weight Water 91.5 Wetting agen 0.5 Sodium borophosphate'. 8.0

The immersion was conducted under conditions for eliminating air bubbles and the wetting agent assures the penetration of the solution into contact with the fibers so that it is absorbed by the fibers. The roll is then placed in a vise and compressed axially at a pressure of, for example, 50 pounds per square inch to force out excess solution and to give an initial form to the roll. The pressed wiper roll is then dried in a circulating air oven at 300 degrees F. for two hours. Upon cooling, it is manipulated or bent, for example by hand, until the initial stifiness has been destroyed and the roll has been restored to approximately the original softness of the cotton cloth pile.

The solder wiping roll according to this invention'is illustrated in the accompanying drawing in which: v

Fig. 1 is a perspective view of a solder wiping roll, having therein the deposit in accordance with this invention.

Fig. 2 is a diametrical axial section through the solder roll.

In these figures, the body 10 of the wiping roll is formed of a number of disks of textile materials such as cotton, joined by the stitching H. Throughout the body 10, the material is impregnated with the deposit from the aforesaid solution, dried, and then manipulated until the roll is restored to approximately the original softness of the cotton cloth pile.

Tungstates and phosphates can be employed It is necessary to employ the fire-proofing agent within a relatively narrow range of concentration both asto the strength of the soluof fire-proofing agent When employing the sodium borophosphate of the above formula, a

tion and as to the quantity introduced into the fibers.

20 percent solution under the identical conditions produced an extremely hard and stiff wiper roll which could not be restored to the necessary flexibility; whereas a percent solution failed to give satisfactory protection against ignition during the prolonged contacts with silver-lead solder. It is preferred to keep the concentration between 6 and 16 percent.-

Various wetting agents can be employed, the

presently preferred wetting agent being Triton- NE, which is a cationic wetting agent of general commercial use.

It is obvious that the invention is not limited to the specific example of practice, but may be employed in many ways within the scope ofthe appended claims.

I claim:

2 '1. A wiper roll for removing excess silver 'lead solder in a soldering machine and resistant against ignition at a solder-fusion temperature exceeding that of the thermal decomposition of organic materials, consisting of fibrous cellulosic textile material constituting a disk, and a solid residue deposited in the fibers thereof; said residue consisting of the deposit from an aqueous solution containing from 6-to 16 percent of fireproofing material selected from the group con- 4 sisting oi' inorganic tungstate. phosphate and borophosphate salts when dried; the periphery of the disk with the deposit therein having essentially the same characteristics of softness and flexibility as the untreated material.

2. A wiper roll for removing excess silverlead solder in a soldering machine and resistant against ignition at a solder-fusion temperature exceeding that of thermal decomposition of organic materials, consisting oi fibrous cellulosic textile material constituting a disk and a solid residue deposited in the fibres thereof; said residue consisting of the deposit from n aqueous solution containing substantially 8 percent of sodium borophosphate when dried; the periph-v ery of the disk with the deposit therein having essentially the same characteristics of softness and flexibility as the untreated material.

3. The process of'making a wiper roll for removing excess silver-lead solder in a soldering machine and resistant against ignition at a solder-fustion temperature exceeding that of thermal decomposition of organic materials, which comprises assembling disks of cellulosic-base cloth, immersing the same in an aqueous solution having a solute consisting of 6 to 16 percent v of sodium borophosphate, pressing at substan-' tially pounds per square inch to eliminate excess solution, drying for substantially two hours at a temperature of substantially 300 degrees F., and manipulating the dried roll until its periphery is soft and flexible.

RALPH A. LARSON. 

